The disclosure relates to lighting systems and more particularly to light source drivers or ballasts for powering LED arrays, fluorescent or high-intensity-discharge (HID) lamps. Many lighting system installations include a user-operated control unit, such as a wall-mounted switch or dimmer control, allowing controlled operation of a light source that is mounted remotely from the control device. Some light source control devices incorporate a variety of advanced features, including the ability to receive and act on control information transmitted to the device, such as from a radio frequency (RF) transmitter to allow a user to set the lights on or off or to a specific dimming level without being near the control unit. The control unit, moreover, may perform profile control for selectively turning lights on or off at certain times in a given day, or may perform lighting control operations based on sensed conditions such as ambient light levels and/or the sensed presence or absence of a person or vehicle in a given area near the light. Such advanced control devices (switch, dimmer) often include microprocessors and other circuitry that must be powered independently of when the lights are on, and thus require a certain amount of quiescent current flow from which to derive the off-state power. However, current flowing across the light source during such an off-state can cause abnormal operation (e.g. flashing or flickering) of the lamp or LED array. Prior attempts to address these problems involved dissipating excess off-state power in a resistive component in series with the control unit and parallel with the light source, but this approach reduces energy efficiency. Thus, there is a need for improved lighting systems to avoid inadvertent off-state flashing while providing quiescent off-state current to power advanced lighting control devices.